Comment 40 for bug 1986781

For documentation purposes,

The critical chain of systemd units/time
before/after the fix, with a fake 'sleep 30'
as the command in casper-md5check.service.

Before:

root@ubuntu-server:/# systemd-analyze critical-chain cloud-final.service
The time when unit became active or started is printed after the "@" character.
The time the unit took to start is printed after the "+" character.

cloud-final.service +492ms
`-multi-user.target @37.968s
  `-casper-md5check.service @7.954s +30.010s
    `-basic.target @7.947s
      `-sockets.target @7.946s
        `-snap.lxd.user-daemon.unix.socket @15.740s
          `-sysinit.target @7.892s
            `-cloud-init.service @5.854s +2.032s
              `-systemd-networkd-wait-online.service @5.835s +6ms
                `-systemd-networkd.service @5.713s +119ms
                  `-network-pre.target @5.709s
                    `-cloud-init-local.service @1.943s +3.765s
                      `-systemd-remount-fs.service @1.172s +130ms
                        `-systemd-journald.socket @988ms
                          `--.mount @942ms
                            `--.slice @941ms

After:

root@ubuntu-server:/# systemd-analyze critical-chain cloud-final.service
The time when unit became active or started is printed after the "@" character.
The time the unit took to start is printed after the "+" character.

cloud-final.service +901ms
`-multi-user.target @21.831s
  `-ssh.service @21.712s +38ms
    `-basic.target @8.255s
      `-sockets.target @8.254s
        `-snap.lxd.user-daemon.unix.socket @17.452s
          `-sysinit.target @8.202s
            `-cloud-init.service @6.970s +1.225s
              `-systemd-networkd-wait-online.service @6.958s +9ms
                `-systemd-networkd.service @6.842s +113ms
                  `-network-pre.target @6.838s
                    `-cloud-init-local.service @1.938s +4.898s
                      `-systemd-remount-fs.service @1.160s +174ms
                        `-systemd-journald.socket @941ms
                          `-system.slice @894ms
                            `--.slice @894ms